Prosthetic mitral valve

ABSTRACT

A prosthetic heart valve having an inflow end and an outflow end includes a stent having a collapsed condition, an expanded condition, and a plurality of cells arranged in circumferential rows. The stent may include one or more securement features. One securement feature may be an anchor arm having a body portion and a free end extending from the body portion, the body portion being coupled to a perimeter of one of the plurality of cells, with the free end extending toward the inflow end in an expanded condition of the anchor arm. Another securement feature may include a flange formed of a braided mesh and having a body portion coupled to the stent and a flared portion adjacent the inflow end of the prosthetic heart valve. A valve assembly is disposed within the stent and has a plurality of leaflets.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No. 15/077,070, filed on Mar. 22, 2016, which claims the benefit of the filing date of U.S. Provisional Patent Application No. 62/137,444 filed Mar. 24, 2015, the disclosures of which are both hereby incorporated by reference herein.

BACKGROUND

The present disclosure relates to heart valve replacement and, in particular, to collapsible prosthetic heart valves. More particularly, the present disclosure relates to collapsible prosthetic heart valves having anchoring features.

Prosthetic heart valves that are collapsible to a relatively small circumferential size can be delivered into a patient less invasively than valves that are not collapsible. For example, a collapsible valve may be delivered into a patient via a tube-like delivery apparatus such as a catheter, a trocar, a laparoscopic instrument, or the like. This collapsibility can avoid the need for a more invasive procedure such as full open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valve structure mounted on a stent. There are two types of stents on which the valve structures are ordinarily mounted: a self-expanding stent and a balloon-expandable stent. To place such valves into a delivery apparatus and ultimately into a patient, the valve is generally first collapsed or crimped to reduce its circumferential size.

When a collapsed prosthetic valve has reached the desired implant site in the patient (e.g., at or near the annulus of the patient's heart valve that is to be replaced by the prosthetic valve), the prosthetic valve can be deployed or released from the delivery apparatus and re-expanded to full operating size. For balloon-expandable valves, this generally involves releasing the entire valve, assuring its proper location, and then expanding a balloon positioned within the valve stent. For self-expanding valves, on the other hand, the stent automatically expands as the sheath covering the valve is withdrawn.

BRIEF SUMMARY

According to one aspect of the disclosure, a prosthetic heart valve has an inflow end and an outflow end. The prosthetic heart valve may include a stent having a collapsed condition, an expanded condition, and a plurality of cells arranged in circumferential rows. The prosthetic heart valve may also include an anchor arm having a body portion and a free end extending from the body portion. The body portion may be coupled to a perimeter of one of the plurality of cells, and the free end may extend toward the inflow end at a spaced distance radially outward from the body portion in an expanded condition of the anchor arm. The prosthetic heart valve may also include a valve assembly disposed within the stent and having a plurality of leaflets.

According to another aspect of the disclosure, a prosthetic heart valve includes an inflow end, an outflow end, and a stent having a collapsed condition, an expanded condition, and a plurality of cells arranged in circumferential rows. The prosthetic heart valve may also include an engaging arm pivotably disposed in one of the plurality of cells adjacent the outflow end, the engaging arm having a first strut coupled to the one cell, a second strut coupled to the one cell, and a third curved strut coupling the first strut to the second strut. The prosthetic heart valve may additionally include a flange formed of a braided mesh and having a body portion coupled to the stent and a flared portion adjacent the inflow end of the prosthetic heart valve. The prosthetic heart valve may further include a valve assembly disposed within the stent and having a plurality of leaflets.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described herein with reference to the drawings, wherein:

FIG. 1 is a highly schematic cutaway representation of a human heart showing various delivery approaches;

FIG. 2 is a highly schematic representation of a native mitral valve and associated cardiac structures;

FIG. 3A is a side view of a prosthetic heart valve according to the prior art;

FIG. 3B is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 3A;

FIG. 4A is a side view of a prosthetic heart valve according to an aspect of the disclosure;

FIG. 4B is a side view of the prosthetic heart valve of FIG. 4A rotated about its longitudinal axis;

FIG. 4C is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 4A;

FIG. 4D is an isolated perspective view of an anchor feature of the prosthetic heart valve of FIG. 4A;

FIG. 4E is a side view of the prosthetic heart valve of FIG. 4A in a stage of manufacture;

FIG. 4F is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 4A in a collapsed condition;

FIG. 4G is a highly schematic representation of the prosthetic heart valve of FIG. 4A implanted into a native mitral valve annulus;

FIG. 4H is a highly schematic bottom view of the outflow end of the prosthetic heart valve of FIG. 4A;

FIG. 4I is a highly schematic bottom view of the outflow end of a prosthetic heart valve according to another aspect of the disclosure;

FIG. 5A is a side view of a prosthetic heart valve according to a further aspect of the disclosure;

FIG. 5B is a side view of the prosthetic heart valve of FIG. 5A rotated about its longitudinal axis;

FIG. 5C is a top view of the inflow end of the prosthetic heart valve of FIG. 5A;

FIG. 5D is a bottom view of the outflow end of the prosthetic heart valve of FIG. 5A;

FIG. 5E is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 5A in the expanded condition;

FIG. 5F is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 5A in the collapsed condition;

FIG. 5G is a highly schematic representation of the prosthetic heart valve of FIG. 5A implanted into a native mitral valve annulus;

FIG. 5H is a highly schematic cross-section of a portion of the flange of the prosthetic heart valve of FIG. 5A;

FIG. 6A is a side view of a prosthetic heart valve according to yet another aspect of the disclosure;

FIG. 6B is a side view of the prosthetic heart valve of FIG. 6A rotated about its longitudinal axis;

FIG. 6C is a bottom perspective view of the outflow end of the prosthetic heart valve of FIG. 6A;

FIG. 6D is a top view of the inflow end of the prosthetic heart valve of FIG. 6A;

FIG. 6E is a highly schematic bottom view of the outflow end of the prosthetic heart valve of FIG. 6A;

FIG. 6F is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 6A in a collapsed condition;

FIG. 6G is a highly schematic representation of the prosthetic heart valve of FIG. 6A implanted into a native mitral valve annulus;

FIG. 7A is a highly schematic bottom view of the outflow end of a prosthetic heart valve according to another aspect of the disclosure;

FIG. 7B is a side view of a prosthetic heart valve according to a further aspect of the disclosure incorporating features of the prosthetic heart valve of FIG. 7A;

FIG. 7C is a side view of the prosthetic heart valve of FIG. 7B rotated about its longitudinal axis;

FIG. 7D is a top view of the inflow end of the prosthetic heart valve of FIG. 7B;

FIG. 7E is a bottom view of the outflow end of the prosthetic heart valve of FIG. 7B;

FIG. 7F is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 7B in the expanded condition;

FIG. 7G is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 7B in the collapsed condition;

FIG. 7H is a highly schematic representation of the prosthetic heart valve of FIG. 7B implanted into a native mitral valve annulus;

FIG. 8A is a side view of a prosthetic heart valve according to yet another aspect of the disclosure;

FIG. 8B is a developed view of a stent used in the prosthetic heart valve of FIG. 8A;

FIG. 8C is a side view of the prosthetic heart valve of FIG. 8A rotated about its longitudinal axis;

FIG. 8D is a side view of the prosthetic heart valve of FIG. 8A rotated further about its longitudinal axis;

FIG. 8E is a bottom view of the outflow end of the prosthetic heart valve of FIG. 8A;

FIG. 8F is a top view of the inflow end of the prosthetic heart valve of FIG. 8A;

FIG. 8G is a highly schematic longitudinal cross-section of the prosthetic heart valve of FIG. 8A in a collapsed condition; and

FIG. 8H is a highly schematic representation of the prosthetic heart valve of FIG. 8A implanted into a native mitral valve annulus.

DETAILED DESCRIPTION

Blood flows through the mitral valve from the left atrium to the left ventricle. As used herein, the term “inflow end,” when used in connection with a prosthetic mitral heart valve, refers to the end of the heart valve closest to the left atrium when the heart valve is implanted in a patient, whereas the term “outflow end,” when used in connection with a prosthetic mitral heart valve, refers to the end of the heart valve closest to the left ventricle when the heart valve is implanted in a patient. Also, as used herein, the terms “substantially,” “generally,” and “about” are intended to mean that slight deviations from absolute are included within the scope of the term so modified. Generally, materials described as being suitable for components in one embodiment may also be suitable for similar or identical components described in other embodiments.

FIG. 1 is a highly schematic cutaway representation of human heart 100. The human heart includes two atria and two ventricles: right atrium 112 and left atrium 122, and right ventricle 114 and left ventricle 124. Heart 100 further includes aorta 110 and aortic arch 120. Disposed between left atrium 122 and left ventricle 124 is mitral valve 130. Mitral valve 130, also known as the bicuspid valve or left atrioventricular valve, is a dual-flap valve that opens as a result of increased pressure in left atrium 122 as it fills with blood. As atrial pressure increases above that of left ventricle 124, mitral valve 130 opens and blood passes into left ventricle 124. Blood flows through heart 100 in the direction shown by arrows “B”.

A dashed arrow, labeled “TA”, indicates a transapical approach of implanting a prosthetic heart valve, in this case to replace the mitral valve. In transapical delivery, a small incision is made between the ribs and into the apex of left ventricle 124 to deliver the prosthetic heart valve to the target site. A second dashed arrow, labeled “TS”, indicates a transseptal approach of implanting a prosthetic heart valve in which the valve is passed through the septum between right atrium 112 and left atrium 122. Other approaches for implanting a prosthetic heart valve are also possible.

FIG. 2 is a more detailed schematic representation of native mitral valve 130 and its associated structures. As previously noted, mitral valve 130 includes two flaps or leaflets, posterior leaflet 136 and anterior leaflet 138, disposed between left atrium 122 and left ventricle 124. Cord-like tendons, known as chordae tendineae 134, connect the two leaflets 136, 138 to the medial and lateral papillary muscles 132. During atrial systole, blood flows from higher pressure in left atrium 122 to lower pressure in left ventricle 124. When left ventricle 124 contracts in ventricular systole, the increased blood pressure in the chamber pushes leaflets 136, 138 to close, preventing the backflow of blood into left atrium 122. Since the blood pressure in left atrium 122 is much lower than that in left ventricle 124, leaflets 136, 138 attempt to evert to the low pressure regions. Chordae tendineae 134 prevent the eversion by becoming tense, thus pulling on leaflets 136, 138 and holding them in the closed position.

FIGS. 3A and 3B are a side view and a longitudinal cross-sectional view of prosthetic heart valve 300 according to the prior art. Prosthetic heart valve 300 is a collapsible prosthetic heart valve designed to replace the function of the native mitral valve of a patient (see native mitral valve 130 of FIGS. 1-2). Generally, prosthetic valve 300 has a substantially cylindrical shape with inflow end 310 and outflow end 312. When used to replace native mitral valve 130, prosthetic valve 300 may have a low profile so as not to interfere with atrial function in the native valve annulus.

Prosthetic heart valve 300 may include stent 350, which may be formed from biocompatible materials that are capable of self-expansion, such as, for example, shape-memory alloys including Nitinol. Stent 350 may include a plurality of struts 352 that form cells 354 connected to one another in one or more annular rows around the stent. Cells 354 may all be of substantially the same size around the perimeter and along the length of stent 350. Alternatively, cells 354 near inflow end 310 may be larger than the cells near outflow end 312. Stent 350 may be expandable to provide a radial force to assist with positioning and stabilizing prosthetic heart valve 300 in the native valve annulus.

Prosthetic heart valve 300 may also include a substantially cylindrical valve assembly 360 including a plurality of leaflets 362 (FIG. 3B) attached to a cuff 364 (FIG. 3A). Leaflets 362 replace the function of native mitral valve leaflets 136 and 138 described above with reference to FIG. 2. That is, leaflets 362 coapt with one another to function as a one-way valve. The valve assembly 360 of prosthetic heart valve 300 may include two or three leaflets, but it should be appreciated that prosthetic heart valve 300 may have more than three leaflets. Both cuff 364 and leaflets 362 may be wholly or partly formed of any suitable biological material, such as bovine or porcine pericardium, or polymers, such as polytetrafluoroethylene (PTFE), urethanes and the like. Valve assembly 360 may be secured to stent 350 by suturing to struts 352 or by using tissue glue, ultrasonic welding or other suitable methods.

When prosthetic heart valve 300 is implanted in a patient, for example at the annulus of native mitral valve 130, it is biased towards an expanded condition, providing radial force to anchor the valve in place. However, if the radial force is too high, damage may occur to heart tissue. If, instead, the radial force is too low, the heart valve may move from its implanted position, for example, into either left ventricle 124 or left atrium 122, requiring emergency surgery to remove the displaced valve. The potential for such movement may be heightened in mitral valve applications, particularly if a low profile valve is used.

Another potential issue with prosthetic heart valves is inadequate sealing between the prosthetic valve and the native tissue. For example, if prosthetic heart valve 300 is implanted at the annulus of mitral valve 130 in a patient, improper or inadequate sealing may result in blood flowing from left ventricle 124 into left atrium 122, even if leaflets 362 of valve assembly 360 are working properly. This may occur, for example, if blood flows in a retrograde fashion between the outer perimeter of prosthetic heart valve 300 and the native tissue at the site of implantation. This phenomenon is known as perivalvular (or paravalvular) leak (“PV leak”).

FIG. 4A is a side view of a prosthetic heart valve 400 in accordance with one embodiment of the disclosure. FIG. 4B shows prosthetic heart valve 400 rotated approximately 180 degrees about its longitudinal axis compared to FIG. 4A. Prosthetic heart valve 400 may be similar or identical to prosthetic heart valve 300 in certain respects. For example, prosthetic heart valve 400 is collapsible and expandable and designed for replacement of a native mitral valve, having a substantially cylindrical shape with an inflow end 410 and an outflow end 412. It should be understood that prosthetic heart valve 400 is not limited to replacement of mitral valves, and may be used to replace other heart valves. Prosthetic heart valve 400 may include stent 450, which may be similar to stent 350, having a plurality of struts 452 that form cells 454 connected to one another in one or more annular rows around stent 450. Stent 450 includes two annular rows of cells 454 of substantially similar size and shape, with nine cells in each row. As illustrated, cells 454 are generally diamond shaped. However, it should be understood that a different number of rows of cells 454, as well as a different number of cells 454 per row, may be suitable. Also, as discussed in relation to stent 350, stent 450 may be formed from a shape memory alloy, such as Nitinol. The struts 452 forming stent 450 may have a diameter of between about 0.020 inches (0.51 mm) and about 0.025 inches (0.64 mm), although other dimensions may be suitable. Forming stent 450 from struts 452 of a relatively large diameter may provide increased stiffness to stent 450, which may provide certain benefits, such as minimizing the deflection of commissure attachment features (CAFs) 466 during normal operation of prosthetic heart valve 400. On the other hand, forming stent 450 from struts 452 of a relatively small diameter may provide increased flexibility to stent 450, which may provide certain benefits, such as the capability to be collapsed to a smaller profile during delivery.

Prosthetic heart valve 400 may also include valve assembly 460 having three leaflets 462 attached to a cylindrical cuff 464. It should be understood that although native mitral valve 130 has two leaflets 136, 138, prosthetic heart valve 400 may have three leaflets, or more or fewer than three leaflets, provided that the leaflets act to allow one-way antegrade blood flow through the prosthetic heart valve 400. Because prosthetic heart valve 400 has three leaflets 462, it also has three CAFs 466, which provide points of attachment for adjacent leaflets 462 to stent 450. It should be understood that prosthetic heart valve 400 may alternatively include a pair of prosthetic leaflets and a corresponding pair of CAFs.

As with stent 350, stent 450 may be expandable to provide a radial force to assist with positioning and stabilizing prosthetic heart valve 400 in the native mitral valve annulus. However, prosthetic valve 400 includes additional securement features in the form of anchor arms 470 that hook under native mitral valve leaflets 136, 138 to help prevent prosthetic heart valve 400 from migrating into left atrium 122.

A single anchor arm 470 is shown in FIG. 4D. Anchor arm 470 may be formed of a single wire 472 bent or otherwise formed into a body portion 471 having a substantially diamond shape. Wire 472 is preferably a shape-memory alloy such as Nitinol. In one example, wire 472 is formed of Nitinol having a diameter of about 0.015 inches (0.38 mm). As with struts 452 of stent 450, the diameter of wire 472 may be increased to provide increased stiffness or decreased to provide increased flexibility. Although the shape of body portion 471 may vary, it preferably corresponds to the geometry of a single cell 454 of stent 450. Wire 472 has two free end portions 474that extend adjacent and substantially parallel to one another, and that are curved or hooked so as to lie at a spaced distance radially outward from body portion 471. Preferably, the tip 476 of each free end portion 474 is blunt and/or rounded to reduce the likelihood of tips 476 damaging the native tissue hooked by anchor arm 470. In addition or alternatively, a blunted and/or rounded end cap 478 may be assembled over or onto the tips 476 of free end portions 474 and fixed to tips 476, for example by welding, to provide an atraumatic tissue contact surface.

Prosthetic heart valve 400 is shown at a stage of manufacture in FIG. 4E to better illustrate the attachment of anchor arms 470 to prosthetic heart valve 400. After valve assembly 460 and cuff 464 have been attached to stent 450, anchor arms 470 may be coupled to prosthetic heart valve 400 at desired locations around stent 450. As shown in FIG. 4E, anchor arms 470 may be positioned within and/or adjacent to a selected cell 454 of stent 450 and connected to the prosthetic heart valve 400, for example by suturing body portion 471 of anchor arm 470 to the struts 452 defining the perimeter of selected cell 454. The sutures coupling anchor arms 470 to prosthetic heart valve 400 may additionally pass through cuff 464. Forces applied to free end portions 474 are transmitted to the body portion 471 of anchor arm 470. With the above-described configuration of anchor arm 470 and its attachment to cell 454, those transmitted forces are distributed over a larger area of stent 450, providing better reinforcement than if free end portions 474 were sewn or otherwise directly connected to stent 450 without the use of body portion 471.

As noted above, wire 472 forming anchor arms 470 is preferably made from a shape-memory alloy. By using a shape-memory alloy, the shape of anchor arms 470 may be set, for example by heat setting, to take the illustrated shape in the absence of applied forces. However, forces may be applied to anchor arms 470 and to prosthetic heart valve 400 generally to reduce radial size and/or bulk of the prosthetic heart valve when in the collapsed condition, which may facilitate intravascular (or other minimally invasive) delivery of the prosthetic heart valve via a delivery device (not shown). For example, as shown in FIG. 4F, prosthetic heart valve 400 may be transitioned to the collapsed condition, with free end portions 474 of anchor arms 470 being distorted or “flipped” to point toward outflow end 412 rather than inflow end 410. Prosthetic heart valve 400 may be maintained in the collapsed condition, for example by a surrounding sheath of a delivery device (not shown), as prosthetic heart valve 400 is delivered to native mitral valve 130. When in a desired position relative to native mitral valve 130, prosthetic heart valve 400 may be released from the delivery device. As constraining forces are removed from prosthetic heart valve 400, it begins to transition to the expanded condition, while anchor arms 470 move to their preset shape. Since anchor arms 470 are shape-set so that their free end portions 474 point toward inflow end 410, anchor arms 470 revert to that shape when released from the delivery device. As the free end portions 474 of anchor arms 470 transition from pointing toward outflow end 412 to pointing toward inflow end 412, native mitral valve leaflets 136, 138 are captured between the free end portions 474 and the body of stent 450, as shown in FIG. 4G. When hooked around native mitral valve leaflets 136, 138, anchor arms 470 help anchor prosthetic heart valve 400 within native valve annulus VA and are particularly effective at resisting migration of the prosthetic heart valve into left atrium 122. Distorting or flipping the anchor arms 470 while prosthetic heart valve 400 is maintained in the collapsed condition may reduce the profile of the collapsed valve, although prosthetic heart valve 400 may alternatively be put in the collapsed condition without distorting or flipping anchor arms 470.

As described above, the stent 450 of prosthetic heart valve 400 may include two circumferential rows of annular cells 454, with each row containing nine cells 454. Although the use of nine cells 454 is merely an example, the use of an odd number of cells 454 in prosthetic heart valves for replacing native mitral valve 130 may cause difficulty in creating symmetry in the positioning of anchor arms 470 on the prosthetic heart valve. For example, it is preferable, although not necessary, to use two anchor arms 470 for each of the two native mitral valve leaflets to better distribute the forces caused by hooking or clamping native the mitral valve leaflets between anchor arms 470 and stent 450. With nine substantially equally-sized cells 454, or any other odd number of similarly sized cells 454, symmetry in the positioning of anchor arms 470 is difficult to achieve. FIG. 4H shows prosthetic heart valve 400 as viewed from outflow end 412. It should be understood that although stent 450 is illustrated as a regular nine-sided polygon (with each side representing a single cell 454), this representation is for purposes of clarity only and prosthetic heart valve 400, including stent 450, may take a substantially cylindrical shape when in the expanded condition. As shown in FIG. 4H, two anchor arms 470 a and 470 b may be coupled to stent 450 at adjacent cells 454, for example on cells 454 on either side of a CAF 466. The remaining two anchor arms 470 c and 470 d cannot be placed on adjacent cells 454 diametrically opposed to anchor arms 470 a and 470 b so as to maintain the symmetry of anchor arms 470. When positioning two pairs of anchor arms on substantially diametrically opposed portions of stent 450, it is preferable to maintain the symmetry of the anchor arms relative to at least one plane P1 dividing prosthetic heart valve 400. As shown in FIG. 4H, for a stent having nine substantially similarly-sized cells, this symmetry may be achieved by coupling the other pair of anchor arms 470 c and 470 d to stent 450 at two cells 454 that are separated by one cell 454. When implanting prosthetic heart valve 400, it is preferable to hook anchor arms 470 a and 470 b under posterior leaflet 136 of native mitral valve 130, with anchor arms 470 c and 470 d hooked under anterior leaflet 138 of native mitral valve 130. With this configuration, one CAF 466 abuts posterior leaflet 136 and two CAFs abut anterior leaflet 138.

The teachings provided above in connection with prosthetic heart valve 400 may be applied to a stent 450′ that is similar to stent 450, but that has an even number of cells 454′. For example, FIG. 4I shows a prosthetic heart valve 400′ that incorporates a stent 450′ having two circumferential rows of twelve cells 454′ having substantially equal sizes. Similar to the illustration of FIG. 4H, stent 450′ in FIG. 4I is shown as a regular twelve-sided polygon for purposes of clarity only, and prosthetic heart valve 400′ and stent 450′ may be substantially cylindrical when in the expanded condition. The use of a stent 450′ having an even number of substantially similarly sized cells 454′ makes it easier to couple a first pair of anchor arms 470 a′ and 470 b ′ to a first side of stent 450′ and a second pair of anchor arms 470 c′ and 470 d′ to a diametrically-opposed second side of stent 450′ while maintaining the symmetry of the anchor arms 470 a′-470 d′ relative to two planes P2, P3. In other words, the circumferential spacing between anchor arms 470 a′ and 470 b ′ may be substantially equal to the spacing between anchor arms 470 c′ and 470 d′, while the circumferential spacing between anchor arms 470 a′ and 470 c′ may be substantially equal to the spacing between anchor arms 470 b ′ and 470 d′. When prosthetic heart valve 400′ is implanted, this symmetry about two planes P2, P3 may provide for a more uniform distribution of forces than prosthetic heart valves exhibiting such symmetry in less than two planes (such as prosthetic heart valve 400 described above). In addition, the twelve-cell configuration may provide for more uniform expansion of the stent compared to the nine-cell configuration.

While prosthetic heart valve 400 may be used as shown and described above in connection with FIGS. 4A-I, a prosthetic heart valve may be provided with additional anchoring and/or sealing elements. For example, FIGS. 5A-D illustrate a prosthetic heart valve 500 that essentially comprises prosthetic heart valve 400 with a flange 580 coupled thereto. Flange 580 may facilitate the anchoring of heart valve 500 within native mitral valve annulus 130 and the prevention of PV leak. Flange 580 may be formed of a material braided to create various shapes and/or geometries to engage tissue. As shown in FIGS. 5A-D, flange 580 includes a plurality of braided strands or wires 586 arranged in three dimensional shapes. In one example, wires 586 form a braided metal fabric that is resilient, collapsible and capable of heat treatment to substantially set a desired shape. One class of materials which meets these qualifications is shape-memory alloys, such as Nitinol. Wires 586 may comprise various materials other than Nitinol that have elastic and/or memory properties, such as spring stainless steel, tradenamed alloys such as Elgiloy® and Hastelloy®, CoCrNi alloys (e.g., tradename Phynox), MP35N®, CoCrMo alloys, or a mixture of metal and polymer fibers. Depending on the individual material selected, the strand diameter, number of strands, and pitch may be altered to achieve the desired shape and properties of flange 580.

Flange 580 may include a body portion 582 terminating at an outflow end of the flange and a flared portion 584 terminating at an inflow end of the flange. Body portion 582 may be formed with a cylindrical or tubular geometry and may be configured to be circumferentially disposed around a portion of stent 450 and/or valve assembly 460. Flange 580 may be coupled to stent 450 (and optionally to valve assembly 460 and/or cuff 464) by sutures, for example. Flange 580 may be alternatively or additionally connected to stent 450 via ultrasonic welds, glue, adhesives, or other suitable means. When coupled to stent 450, body portion 582 of flange 580 is nearer outflow end 512 and flared portion 584 is nearer inflow end 510. When in the expanded condition, flared portion 584 extends a greater distance radially outwardly from the longitudinal axis L of prosthetic heart valve 500 than body portion 582. In other words, as shown in FIG. 5C, flared portion 584 may have a diameter D1 that is greater than the diameter D2 of body portion 582 when prosthetic heart valve 500 is in the expanded condition. In addition, the distance which flared portion 584 extends radially outwardly from longitudinal axis L may increase nearer inflow end 510.

Flange 580 may be preset to take the illustrated trumpet shape in the absence of external forces. As with stent 450 and anchor arms 470, flange 580 may be collapsed to a decreased profile to facilitate minimally invasive delivery. For example, prosthetic heart valve 500 may be transitioned from the expanded condition (FIGS. 5A-E) to the collapsed condition (FIG. 5F) and maintained in the collapsed condition by a surrounding sheath of a delivery device. Anchors 470 may flip and point toward outflow end 512 as described in connection with FIG. 4F, and flange 580 may collapse radially inwardly and become substantially cylindrical and/or significantly less flared than in the expanded condition. Body 582 of flange 580 may be positioned between anchor arms 470 and the remainder of stent 450. Prosthetic heart valve 500 may be delivered to the implant site in the collapsed condition and, when in the desired position relative to native mitral valve 130, transitioned to the expanded condition, for example by removing the surrounding sheath of the delivery device. During the transition from the collapsed condition to the expanded condition, anchor arms 470 revert to the preset shape as described in connection with FIG. 4F, capturing native mitral valve leaflets 136, 138 between anchor arms 470 and corresponding portions of stent 450. Flange 580 also transitions from the collapsed condition to the expanded condition, assuming its preset shape shown in FIG. 5G. When implanted and in the expanded condition, flange 580 provides a large surface area to help anchor prosthetic valve 500 within native valve annulus VA, and may be particularly effective at resisting movement of prosthetic heart valve 500 toward left ventricle 124. Specifically, flange 580 has an expanded diameter that is too large to pass through native valve annulus VA. Because flange 580 is coupled to stent 450, prosthetic heart valve 500 is restricted from migrating into left ventricle 124 during normal operation of prosthetic heart valve 500. Thus, the combination of anchor arms 470 engaged with the mitral valve leaflets, and flange 580 engaged with the tissue on the atrial side of the mitral valve annulus, helps to securely anchor prosthetic heart valve 500 within the mitral valve annulus and limits its migration toward either the left atrium or the left ventricle.

In addition to providing anchoring capabilities, flange 580 may improve sealing between prosthetic heart valve 500 and native valve annulus VA. In particular, as shown in FIG. 5H, flange 580 may be formed with an outer layer 580 a and an inner layer 580 b, for example by folding one portion of braided wires 586 over another portion of braided wires 586. A fabric layer 588, such as a polyester fabric, may be inserted or sandwiched between outer layer 580 a and inner layer 580 b. Fabric layer 588 may enhance tissue ingrowth into prosthetic heart valve 500 after implantation and may also enhance the fluid seal, and thus help prevent PV leak, between the outer diameter of prosthetic heart valve 500 and the adjacent portions of native mitral valve annulus VA. Although flange 580 is described as being folded over onto itself, alternative configurations may be suitable for holding fabric layer 588, for example by weaving or braiding two separate layers of braided wires 586 together. In a variation hereof, a single fabric layer 588 may be applied to the outside surface of flange 580, to the inside surface of flange 580, or to both the outside and inside surfaces of flange 580 to improve sealing between prosthetic heart valve 500 and native valve annulus VA.

FIG. 6A is a side view of prosthetic heart valve 600 in accordance with a further embodiment of the disclosure. FIG. 6B illustrates prosthetic heart valve 600 rotated approximately 90 degrees about its longitudinal axis compared to FIG. 6A. Prosthetic heart valve 600 may be similar to prosthetic heart valve 300 in certain respects. For example, prosthetic heart valve 600 is collapsible and expandable and designed for replacement of a native mitral valve, having a substantially cylindrical shape with an inflow end 610 and an outflow end 612. Prosthetic heart valve 600 may also include a valve assembly having three leaflets attached to a cylindrical cuff, in substantially the same manner as described above in connection with prosthetic heart valve 400. It should be understood that prosthetic heart valve 600 is not limited to replacement of mitral valves, and may be used to replace other heart valves.

Prosthetic heart valve 600 may include stent 650, which generally extends between inflow end 610 and outflow end 612 and includes a plurality of struts 652 forming two circumferential rows of cells 653 a, 653 b. CAFs 666 may be included near outflow end 612. First row of cells 653 a is disposed adjacent outflow end 612 and includes fully symmetric cells 654 alternating with second cells 655. Fully symmetric cells 654 may be substantially diamond-shaped and include four substantially straight struts 654 a-d of equal length. Cells 654 are fully symmetric in that they are symmetric about a vertical line extending from the intersection of struts 654 a and 654 b to the intersection of struts 654 c and 654 c, and about a horizontal line extending from the intersection of struts 654 a and 654 c to the intersection of struts 654 b and 654 d. Cells 655 may include a pair of substantially straight struts 655 a, 655 b which form a V-shape attached to two substantially curved struts 655 c, 655 d. Cells 655 are partially symmetric in that they are symmetric only about a vertical line extending from the intersection of struts 655 a and 655 b to the intersection of struts 655 c and 655 d. Engaging arms 670 may be nested within each cell 655. Engaging arms 670 may be pivotably connected to cells 655 and configured to engage portions of heart tissue (e.g., native mitral valve leaflets) when prosthetic heart valve 600 is deployed in a patient, similar to anchor arms 470 described above. Second row of cells 653 b may include a plurality of asymmetric cells 656 formed by two struts shared with cells from first row 653 a (e.g., struts 654 c and 655 d or struts 654 d and 655 c) and two substantially straight struts 656 a, 656 b. Second row of cells 653 b may also include a plurality of fully symmetric cells 657 substantially similar or identical to fully symmetric cells 654.

As shown in FIGS. 6A-E, stent 650 is formed of two rows of cells, each row having twelve cells and is thus referred to as a twelve-cell configuration. The considerations regarding the placement of engaging arms 670 around the circumference of stent 650 are similar to those described above with respect to the placement of anchor arms 470′ on twelve-cell stent 450′. In particular, first row of cells 653 a may include two sets of three fully symmetric cells 654 on diametrically opposing portions of stent 650. Between each set of fully symmetric cells 654 may be another set of three cells, each set including two partially symmetric cells 655 having engaging arms 670 nested therein with a fully symmetric cell 654 positioned between the two partially symmetric cells 655. Because stent 650 has an even number of cells in first circumferential row 653 a, in this case twelve, engaging arms 670 may be positioned symmetrically relative to two planes P4, P5, each bisecting prosthetic heart valve 600.

Each engaging arm 670 may be formed of a shape-memory alloy, and is preferably formed from the same material as stent 650. For example, stent 650 and engaging arms 670 may be formed from a single tube of Nitinol, for example by laser cutting. Engaging arms 670 may include two substantially parallel struts 670 a, 670 b connected to one another by rounded strut 670 c. Engaging arms 670 may be shape set, for example by heat setting, so that in the absence of external forces, the free end of engaging arm 670 defined by strut 670 c is positioned radially outwardly from the partially symmetric cell 655 in which the engaging arm is nested. However, forces may be applied to engaging arms 670 and to prosthetic heart valve 600 generally to reduce the radial size and/or bulk of the prosthetic heart valve when in the collapsed condition, which may facilitate intravascular (or other minimally invasive) delivery of the prosthetic heart valve via a delivery device (not shown).

For example, as shown in FIG. 6F, prosthetic heart valve 600 may be transitioned to the collapsed condition, with engaging arms 670 constrained so that each engaging arm is positioned substantially within a surface defined by the partially symmetric cell 655 in which the engaging arm is nested. In other words, when in the collapsed condition shown in FIG. 6F, engaging arms 670 do not protrude a significant distance radially outwardly from stent 650. Prosthetic heart valve 600 may be held in the collapsed condition by the delivery device as it is delivered to native mitral valve 130. When in a desired position relative to native mitral valve 130, prosthetic heart valve 600 may be released from the delivery device. As constraining forces are removed from prosthetic heart valve 600, it begins to transition to the expanded condition, while engaging arms 670 move to their preset shape projecting radially outwardly from the rest of stent 650. Once engaging arms 670 are in their preset shape, prosthetic heart valve 600 may be pulled (or pushed) toward left atrium 122 until engaging arms 670 hook under native mitral valve leaflets 136, 138, as shown in FIG. 6G. The rounded configuration of strut 670 c may reduce the likelihood of trauma to native tissue captured by engaging arms 670. When hooked around native mitral valve leaflets 136, 138, engaging arms 670 help anchor prosthetic heart valve 600 within native valve annulus VA and resist its migration into left atrium 122.

Similar to stent 450, stent 650 of prosthetic heart valve 600 may be formed with an odd number of cells in each circumferential row rather than an even number. Stent 650′, shown in FIG. 7A, is similar to stent 650 with the exception that it has two annular rows of nine cells each. With this configuration, engaging arms 670′ may be situated around the circumference of stent 650′ so that they are symmetric relative to one plane P6. Prosthetic heart valve 700, shown in FIGS. 7B-H, incorporates flange 780 with stent 650′. Flange 780, and its relation to stent 650′, may be similar or identical to flange 580 of prosthetic heart valve 500 and its relation to stent 450′. For example, flange 780 may include a plurality of braided strands or wires 786 arranged in three dimensional shapes. The body portion 782 and flared portion 784 of flange 780 may also be similar or identical to the corresponding portions of flange 580, with body portion 782 being coupled to stent 650′ by sutures, for example. Similar to prosthetic heart valve 500, engaging arms 670′ of prosthetic heart valve 700 are shape-set so that, in the absence of applied forces, body 782 of flange 780 is positioned between the struts 670 a′-670 c′ forming engaging arms 670′ and the remainder of stent 650′. Similarly, prosthetic heart valve 700 may also include a valve assembly having three leaflets attached to a cylindrical cuff, in substantially the same manner as described above in connection with prosthetic heart valves 400 and 600.

Prosthetic heart valve 700 may be delivered to the implant site in the collapsed condition, shown in FIG. 7G, and transitioned to the expanded condition near native mitral valve 130. Engaging arms 670′ revert to the preset shape in a similar manner as described above in connection with the engaging arms of prosthetic heart valve 600, capturing native mitral valve leaflets 136, 138 between engaging arms 670′ and corresponding portions of stent 650′, as shown in FIG. 7H. Flange 780 also transitions from the collapsed condition to the expanded condition, assuming its preset shape shown in FIG. 7H. Similar to flange 580 of prosthetic heart valve 500, flange 780 of prosthetic heart valve 700 expands to help anchor prosthetic valve 700 within native valve annulus VA. Flange 780 may also include a fabric layer, similar to fabric layer 588, to provide additional sealing against PV leak. As with prosthetic heart valve 500 described above, the combination of engaging arms 670′ and flange 780 securely anchors prosthetic heart valve 700 within native valve annuls VA and limits its migration toward either the left atrium or the left ventricle.

A prosthetic heart valve 800 according to still another embodiment of the disclosure, and a stent 850 for use prosthetic heart valve 800, are illustrated in FIGS. 8A-H. Prosthetic heart valve 800 may be similar to prosthetic heart valve 700, but incorporates a flared stent rather than a braided flange, as described below. As should be understood, prosthetic heart valve 800 may also include a valve assembly having three leaflets attached to a cylindrical cuff, in substantially the same manner as described above in connection with prosthetic heart valves 400, 600, and 700.

FIG. 8A is side view of prosthetic heart valve 800. Prosthetic heart valve 800 is collapsible and expandable and designed for replacement of a native mitral valve. Prosthetic heart valve 800 has an inflow end 810, an outflow end 812, a substantially cylindrical portion nearer outflow end 812, and a flared portion nearer inflow end 810 when in the expanded condition. It should be understood that prosthetic heart valve 800 is not limited to replacement of mitral valves, and may be used to replace other heart valves.

Prosthetic heart valve 800 includes stent 850, which has similar securement features as prosthetic heart valves 600 and 700 described above. In particular, and as best shown in FIG. 8B, stent 850 includes a plurality of struts 852 forming three circumferential rows of cells 853 a, 853 b, and 853 c. CAFs 866 may be included near outflow end 812. First row of cells 853 a is disposed adjacent outflow end 812 and includes fully symmetric cells 854 and partially symmetric cells 855 at selected positions within first row 853 a, similar to the first row of cells 653 a of prosthetic heart valve 600. Fully symmetric cells 854 may be substantially diamond-shaped and include four substantially straight struts 854 a-d of equal length. Cells 854 are fully symmetric in that they are symmetric about a vertical line extending from the intersection of struts 854 a and 854 b to the intersection of struts 854 c and 854 c, and about a horizontal line extending from the intersection of struts 854 a and 854 c to the intersection of struts 854 b and 854 d. Cells 855 may include a pair of substantially straight struts 855 a, 855 b which form a V-shape attached to two substantially curved struts 855 c, 855 d. Cells 855 are partially symmetric in that they are symmetric only about a vertical line extending from the intersection of struts 855 a and 855 b to the intersection of struts 855 c and 855 d. Engaging arms 870 may be nested within each cell 855. Engaging arms 870 are pivotably connected to cells 855 and may be configured to engage portions of heart tissue (e.g., native mitral valve leaflets) when prosthetic heart valve 800 is deployed in a patient, similar to engaging arms 670 described above. Second row of cells 853 b may include a plurality of asymmetric cells 856 formed by two struts shared with cells from first row 853 a (e.g., struts 854 c and 855 d or struts 854 d and 855 c) and two substantially straight struts 856 a, 856 b. Cells 856 may also include runners 859, which connect cells 858 to adjacent cells 854 or 855. Second row of cells 853 b may also include one or more fully symmetric cells 857 substantially similar or identical to fully symmetric cells 854, although the dimensions of fully symmetric cells 857 may be different than those of fully symmetric cells 854. Third row of cells 853 c is positioned adjacent inflow end 810 and may include a plurality of enlarged substantially diamond-shaped cells 858 that provide a flared shape when prosthetic heart valve 800 is in the expanded condition, as described in greater detail below. It should also be noted that the ends of cells 858 nearest inflow end 810 may be blunted or otherwise rounded, rather than V-shaped.

As shown in FIGS. 8A-D, the three rows of cells forming stent 850 each have nine cells. The considerations regarding the placement of engaging arms 870 around the circumference of stent 850 are similar to those previously discussed with respect to prosthetic heart valve 700, which also has a nine-cell configuration. However, it should be understood that prosthetic heart valve 800 may alternatively take a configuration with a different odd number of cells, or an even number of cells, such as a twelve-cell configuration in which the engaging arms are placed at positions substantially similar to those for prosthetic heart valve 600, shown in FIG. 6E and described above. As shown, first row of cells 853 a may include two partially symmetric cells 855 adjacent to one another, each having an engaging arm 870 nested therein. First row of cells 853 a may also include, substantially diametrically opposed to adjacent cells 855, two additional partially symmetric cells 855 separated by a single fully symmetric cell 854, each of the two additional partially symmetric cells 855 having an engaging arm 870 nested therein.

The structure of engaging arms 870 may be substantially similar to the structure of engaging arms 670. In other words, each engaging arm 870 may be formed of a shape-memory alloy, and is preferably formed from the same material as stent 850. Engaging arms 870 may include two substantially parallel struts 870 a, 870 b connected to one another by rounded strut 870 c. Engaging arms 870 may be shape set in a similar manner to engaging arms 670 so that the free end of each engaging arm 870 defined by rounded strut 870 c is positioned radially outwardly from the partially symmetric cell 855 in which the engaging arm is nested. However, forces may be applied to engaging arms 870 and to prosthetic heart valve 800 generally to reduce the radial size and/or bulk of the prosthetic heart valve when in the collapsed condition, which may facilitate intravascular (or other minimally invasive) delivery of the prosthetic heart valve via a delivery device (not shown).

In the expanded condition of prosthetic heart valve 800, the cells in the third row 853 c and portions of the cells in the second row 853 b flare radially outwardly to form a flared section 880. At the same time, the cells in the first row 853 a and other portions of the cells in the second row 853 b form a substantially cylindrical section 882. With this expanded configuration, the diameter of inflow end 810 of stent 850 is greater than the diameter of outflow end 812. Flared section 880 may function to help anchor prosthetic heart valve 800 in native mitral valve annulus VA and to prevent PV leak, as described in greater detail below, in a manner similar to the flanges described above in connection with prosthetic heart valves 500 and 700.

As shown in FIG. 8G, prosthetic heart valve 800 may be transitioned to the collapsed condition, with engaging arms 870 constrained so that each engaging arm 870 is positioned substantially within a surface defined by the partially symmetric cell 855 in which the engaging arm is nested. Flared section 880 may also collapse to a substantially cylindrical profile. Prosthetic heart valve 800 may be held in the collapsed condition by the delivery device as it is delivered to native mitral valve 130. When positioned as desired relative to native mitral valve 130, prosthetic heart valve 800 may be released from the delivery device. As constraining forces are removed from prosthetic heart valve 800, it begins to transition to the expanded condition, while engaging arms 870 and flared section 880 revert to their preset shapes projecting radially outwardly from the rest of stent 850. Once engaging arms 870 are in their preset shape, prosthetic heart valve 800 may be pulled (or pushed) toward left atrium 122 until engaging arms 870 hook under native mitral valve leaflets 136, 138, as shown in FIG. 8H. It is preferable that the pair of engaging arms 870 nested within immediately adjacent partially symmetric cells 855 be hooked under posterior leaflet 136 of native mitral valve 130, with the pair of engaging arms 870 separated by a fully symmetric cell 854 being hooked under anterior leaflet 138 of native mitral valve 130. With this configuration, two CAFs 866 abut posterior leaflet 136 and one CAF abuts anterior leaflet 138. It should be understood that in this embodiment, as well as in other embodiments, the positioning of the prosthetic heart valve 800 may alternatively be such that two CAFs 866 abut anterior leaflet 138 and one CAF 866 abuts posterior leaflet 136. As flared section 880 transitions from the collapsed condition to the expanded condition, it begins to expand radially outwardly to the shape illustrated in FIG. 8A. When implanted and in the expanded condition, flared section 880 provides a large surface area to help anchor prosthetic valve 800 within native valve annulus VA, and may be particularly effective at resisting movement of prosthetic heart valve 800 toward left ventricle 124. Specifically, flange 880 has an expanded diameter that is too large to pass through native valve annulus VA. It will therefore be apparent that the combination of engaging arms 870 and flange 880 helps securely anchor prosthetic heart valve 800 within the mitral valve annulus VA and limit its migration toward either the left ventricle of the left atrium.

According to one aspect of the disclosure, a prosthetic heart valve having an inflow end and an outflow end, comprises:

-   -   a stent having a collapsed condition, an expanded condition, and         a plurality of cells arranged in circumferential rows;     -   an anchor arm having a body portion and a free end extending         from the body portion, the body portion being coupled to a         perimeter of one of the plurality of cells, and the free end         extending toward the inflow end at a spaced distance radially         outward from the body portion in an expanded condition of the         anchor arm; and     -   a valve assembly disposed within the stent and having a         plurality of leaflets; and/or     -   the anchor arm comprises a wire, the body portion being formed         by a center portion of the wire and the free end comprising two         end portions of the wire on opposite sides of the center         portion; and/or     -   the anchor arm includes an atraumatic end cap coupled to the two         end portions of the wire; and/or     -   the anchor arm is sutured to the one cell; and/or     -   the one cell has a shape in the expanded condition of the stent         and the body portion of the anchor arm has a shape in the         expanded condition of the anchor arm that is substantially the         same as the cell shape; and/or     -   the one cell is substantially diamond-shaped in the expanded         condition of the stent and the body portion of the anchor arm is         substantially diamond-shaped in the expanded condition of the         anchor arm; and/or     -   a flange formed of a braided mesh and having a body portion         coupled to the stent and a flared portion adjacent the inflow         end of the prosthetic heart valve; and/or     -   the flared portion of the flange has a first diameter in an         expanded condition of the flange and the body portion of the         flange has a second diameter in the expanded condition of the         flange smaller than the first diameter; and/or     -   the flange includes a first braided mesh layer, a second braided         mesh layer, and a layer of fabric between the first layer and         the second layer; and/or     -   the flared portion of the flange terminates at an inflow end of         the flange and the body portion of the flange terminates at an         outflow end of the flange, the outflow end of the flange being         positioned between the free end portion of the anchor arm and         the body portion of the anchor arm in the expanded condition of         the stent; and/or     -   the plurality of cells include an odd number of cells arranged         in a first circumferential row, four anchor arms being         positioned in the first circumferential row so that a first pair         of the anchor arms is symmetrical to a second pair of the anchor         arms relative to a plane bisecting the prosthetic heart valve;         and/or     -   the plurality of cells include an even number of cells arranged         in a first circumferential row, four anchor arms being         positioned in the first circumferential row so that a first pair         of the anchor arms is symmetrical to a second pair of the anchor         arms relative to a first plane bisecting the prosthetic heart         valve, and a third pair of the anchor arms is symmetrical to a         fourth pair of the anchor arms relative to a second plane         orthogonal to the first plane.

According to another aspect of the disclosure, a prosthetic heart valve having an inflow end and an outflow end, comprises:

-   -   a stent having a collapsed condition, an expanded condition, and         a plurality of cells arranged in circumferential rows;     -   an engaging arm pivotably disposed in one of the plurality of         cells adjacent the outflow end, the engaging arm having a first         strut coupled to the one cell, a second strut coupled to the one         cell, and a third curved strut coupling the first strut to the         second strut;     -   a flange formed of a braided mesh and having a body portion         coupled to the stent and a flared portion adjacent the inflow         end of the prosthetic heart valve; and     -   a valve assembly disposed within the stent and having a         plurality of leaflets; and/or     -   the third strut defines a free end of the engaging arm extending         toward the inflow end of the prosthetic heart valve; and/or     -   the free end of the engaging arm extends radially outwardly from         the one cell in the expanded condition of the stent;     -   the flared portion of the flange terminates at an inflow end of         the flange and the body portion of the flange terminates at an         outflow end of the flange, the outflow end of the flange being         positioned between the free end of the engaging arm and the one         cell in the expanded condition of the stent; and/or     -   the flared portion of the flange has a first diameter in an         expanded condition of the flange and the body portion of the         flange has a second diameter in the expanded condition of the         flange smaller than the first diameter; and/or     -   the flange includes a first braided mesh layer, a second braided         mesh layer, and a layer of fabric between the first layer and         the second layer; and/or     -   the plurality of cells include an odd number of cells arranged         in a first circumferential row, four engaging arms being         positioned in the first circumferential row so that a first pair         of the engaging arms is symmetrical to a second pair of the         engaging arms relative to a plane bisecting the prosthetic heart         valve; and/or     -   the plurality of cells include an even number of cells arranged         in a first circumferential row, four engaging arms being         positioned in the first circumferential row so that a first pair         of the engaging arms is symmetrical to a second pair of the         engaging arms relative to a first plane bisecting the prosthetic         heart valve, and a third pair of the engaging arms is         symmetrical to a fourth pair of the engaging arms relative to a         second plane orthogonal to the first plane.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. In addition, features of embodiments described herein may be combined with features of other embodiments described herein without departing from the scope of the invention. 

1. A prosthetic heart valve having an inflow end and an outflow end, comprising: a stent having a collapsed condition, an expanded condition, and a plurality of cells arranged in a plurality of circumferential rows; a plurality of engaging arms each pivotably disposed in a corresponding one of the plurality of cells adjacent the outflow end, the engaging arms each having a first strut coupled to the one cell, a second strut coupled to the one cell, and a third curved strut coupling the first strut to the second strut; and a valve assembly disposed within the stent and having a plurality of leaflets.
 2. The prosthetic heart valve of claim 1, wherein the third struts defines free ends of the engaging arms extending toward the inflow end of the prosthetic heart valve.
 3. The prosthetic heart valve of claim 2, wherein the free ends of the engaging arms extend radially outwardly from the corresponding one cell in the expanded condition of the stent.
 4. The prosthetic heart valve of claim 3, further comprising a flange formed of a braided mesh and having a body portion coupled to the stent and a flared portion adjacent the inflow end of the prosthetic heart valve.
 5. The prosthetic heart valve of claim 4, wherein the flared portion of the flange terminates at an inflow end of the flange and the body portion of the flange terminates at an outflow end of the flange, the outflow end of the flange being positioned between the free end of the engaging arm and the one cell in the expanded condition of the stent.
 6. The prosthetic heart valve of claim 4, wherein the flared portion of the flange has a first diameter in an expanded condition of the flange and the body portion of the flange has a second diameter in the expanded condition of the flange smaller than the first diameter.
 7. The prosthetic heart valve of claim 4, wherein the flange includes a first braided mesh layer, a second braided mesh layer, and a layer of fabric between the first layer and the second layer.
 8. The prosthetic heart valve of claim 1, wherein the plurality of cells includes an odd number of cells arranged in a first circumferential row, first, second, third, and fourth engaging arms being positioned in the first circumferential row so that the first and second engaging arms are symmetrical to the third and fourth engaging arms relative to a plane bisecting the prosthetic heart valve.
 9. The prosthetic heart valve of claim 1, wherein the plurality of cells includes an even number of cells arranged in a first circumferential row, first, second, third, and fourth engaging arms being positioned in the first circumferential row so that the first and second engaging arms are symmetrical to the third and fourth engaging arms relative to a first plane bisecting the prosthetic heart valve, and the first and third engaging arms are symmetrical to the second and fourth engaging arms relative to a second plane orthogonal to the first plane.
 10. The prosthetic heart valve of claim 1, wherein the plurality of circumferential rows of cells includes a first row of cells adjacent the outflow end and a second row of cells directly adjacent the first row of cells.
 11. The prosthetic heart valve of claim 1, wherein the plurality of circumferential rows of cells includes a first row of cells adjacent the outflow end, the first row of cells including a plurality of fully symmetric diamond-shaped cells formed of first, second, third, and fourth cell struts, the fully symmetric diamond-shaped cells being symmetric about a vertical line extending between a first intersection of the first and second cell struts and a second intersection of the third and fourth cell struts in the expanded condition of the stent, the fully symmetric diamond-shaped cells being symmetric about a horizontal line extending between a third intersection of the first and third cell struts and a fourth intersection of the second and fourth cell struts in the expanded condition of the stent.
 12. The prosthetic heart valve of claim 11, wherein the first, second, third, and fourth cell struts are each substantially straight in the expanded condition of the stent.
 13. The prosthetic heart valve of claim 11, wherein the first row of cells includes a plurality of partially symmetric cells formed of fifth, sixth, seventh, and eighth cell struts, the partially symmetric cells being symmetric about a vertical line extending between a fifth intersection of the fifth and sixth cell struts and a sixth intersection of the seventh and eighth cell struts in the expanded condition of the stent, the partially symmetric cells being asymmetrical about a horizontal line extending between a seventh intersection of the fifth and seventh cell struts and an eighth intersection of the sixth and eighth cell struts in the expanded condition of the stent.
 14. The prosthetic heart valve of claim 13, wherein the fifth and sixth cell struts are substantially straight in the expanded condition of the stent, and the seventh and eighth cell struts are substantially curved in the expanded condition of the stent.
 15. The prosthetic heart valve of claim 13, wherein the plurality of engaging arms are positioned only within corresponding ones of the partially symmetric cells.
 16. The prosthetic heart valve of claim 13, wherein each partially symmetric cell is positioned between two circumferentially adjacent fully symmetric cells.
 17. The prosthetic heart valve of claim 13, wherein the plurality of circumferential rows of cells includes a second circumferential row of cells, the second circumferential row of cells including a plurality of fully asymmetric cells formed of a ninth cell strut common to one of the fully symmetric cells, a tenth cell strut common to one of the partially symmetric cells, and eleventh and twelfth cell struts, the fully asymmetric cells being asymmetric about a vertical line extending between a ninth intersection of the ninth and tenth cell struts and a tenth intersection of the eleventh and twelfth cell struts in the expanded condition of the stent, the fully asymmetric cells being asymmetric about a horizontal line extending between an eleventh intersection of the ninth and the eleventh cell struts and a twelfth intersection of the tenth and the twelfth cell struts in the expanded condition of the stent.
 18. The prosthetic heart valve of claim 17, wherein the plurality of circumferential rows of cells includes only the first circumferential row of cells and the second circumferential row of cells.
 19. The prosthetic heart valve of claim 1, wherein the plurality of leaflets includes three leaflets.
 20. The prosthetic heart valve of claim 1, wherein the prosthetic heart valve is configured to replace a native mitral valve. 